Background: Little data exist regarding comparison of efficacy and safety between tenofovir disoproxil fumarate (TDF) and Telbivudine (LdT) in late pregnancy to prevent hepatitis B mother-to-child transmission (MTCT) in real-world settings.Methods: We retrospectively included HB-s antigen (HBsAg) positive mothers with HBV DNA ≥2*105IU/mL to receive TDF or LdT after gestational weeks 24~32 weeks. All infants received standard immunoprophylaxis. Primary outcomes were MTCT rates at infants' age of

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... 52 weeks and safety of TDF or LdT use. Secondary outcomes were the decline of HBV-DNA levels at delivery and rates of on-treatment and off-treatment alanine aminotransferase (ALT) elevation>2 upper limits of normal (ULN) during the study.Results: Of 1407 women, 209 received TDF and 1198 received LdT treatment. There were no differences between mean duration of TDF and LdT treatment (TDF vs. LdT: 11.76±2.20 weeks vs 11.64±2.79 weeks, p=0.47). At birth, 213 (9.8%) infants in the TDF-group were HBsAg positive, lower than 1180 (20.8%) in the LdT-group (p<0.001). Among 1405 infants (TDF/LdT=213/1192) of the 1385 (TDF/LdT=205/1180) women completed the 52-weeks study, intention‐to‐treat analysis indicated one infant (0.5 %) was lost to follow-up in TDF treated mothers and three (0.3 %) in LDT treated mothers (p=0.48). On-treatment analysis indicated no HBsAg positive infants in the two groups. Levels of HBV-DNA decline in TDF-treated mothers were observed comparable to LdT-treated mothers (4.05±0.93 log10IU/mlvs.3.99±1.30 log10IU/ml, p=0.50). TDF-treated mothers had complained more symptoms of the digestive system and less arthralgia than LdT-treated mothers. All adverse events in the two groups were grade I-II. Alanine aminotransferase (ALT) elevation(>2ULN) in TDF-treated mothers were lower than in LdT-treated mothers (7.3% vs.15.7%, p<0.05).Conclusions: TDF and LdT use in late pregnancy for highly viremic mothers was equally effective in reducing MTCT. However, TDF has fewer ALT abnormalities than LdT during treatment and is the preferred choice.